Head to head

Tirzepatide vs Retatrutide

An approved dual agonist against a triple agonist still in trials.

Tirzepatide hits GIP and GLP-1 receptors and is approved. Retatrutide adds glucagon-receptor activity and posted larger weight-loss numbers in Phase 2, but it is unapproved and its Phase 3 results were not yet published at review. The two have never been compared directly.

Measure	TirzepatideGIP / GLP-1 dual receptor agonist	RetatrutideGIP / GLP-1 / glucagon triple agonist
Best evidence	Established	Clinical
Human-tested claims	1 of 1	1 of 2
Status	Approved	Research-only
Cited sources	3	4

Where the evidence lands

Retatrutide's Phase 2 number is bigger, but it comes from a 48-week trial of a few hundred people, against tirzepatide's multiple Phase 3 trials, label, and real-world exposure. Cross-trial comparisons of weight loss are unreliable because populations, durations and dropout differ. The honest reading is that retatrutide is the more promising molecule and tirzepatide is the proven one, and that gap will not close until the triple agonist's pivotal data and label are public.

Where they differ

Each row cites a fixed record. Numbers from different trials are not directly comparable, and the rows say so where that applies.

Aspect	Tirzepatide	Retatrutide
Receptors[1]	Dual GIP and GLP-1 receptor agonist.	Triple GIP, GLP-1 and glucagon receptor agonist.
Best weight-loss result[2]	Mean 20.9% reduction at 72 weeks on the top dose vs 3.1% on placebo (SURMOUNT-1, Phase 3).	Mean around 24.2% at 48 weeks on the top dose (Phase 2). Different trial, not directly comparable.
Evidence stage[3]	Pivotal Phase 3 program complete and on the label.	Phase 3 program complete; results not yet published at review.
Status[3]	FDA-approved (Mounjaro, Zepbound).	Investigational. Filing for approval planned for 2027.
Open safety questions[2]	Characterized on the label: gastrointestinal effects, class thyroid warning.	Glucagon-receptor activity puts heart rate and glucose under scrutiny; Phase 3 was designed to answer that.

What each is studied for

The efficacy claims from each monograph, with their tiers. Follow the entry for sources and safety.

Tirzepatide

Established
Produced ~20.9% mean body-weight reduction at 72 weeks on the top dose vs ~3.1% on placebo (SURMOUNT-1).

Retatrutide

Clinical
83% of participants lost ≥15% body weight and mean loss reached ~24.2% at 48 weeks on the top dose in a Phase 2 RCT.
Preclinical
Triple agonism at the GLP-1, GIP, and glucagon receptors distinguishes it mechanistically from dual agonists.

Frequently asked

Does retatrutide beat tirzepatide?

Nobody knows. There is no head-to-head trial, and comparing a Phase 2 number with a Phase 3 number from a different population is the kind of thing this site exists to discourage.

References

The monographs

Written by Twenty Residues editorial. Medical review: pending; a named reviewer is being assigned.

Last updated October 1, 2026.

Tiers are explained in the Standard. Spot an error? Report a correction.